Visual mental imagery helps people to perform a host of tasks, including remembering events, spatial reasoning, and language comprehension. The images produced in the service of these activities are the result of a complex information processing system. This system can be conceptualized as being composed of a set of distinct "processing subsystems," each of which performs a specific cognitive operation (e.g., shifting the orientation of an imaged object, activating stored visual memories to create an image, encoding the relative location of part of the imaged object). The research described here makes use of a theory of these processing subsystems that draws on concepts from artificial intelligence and facts about the neurological substrate of high.level vision. The research will characterize the relative efficacy of eleven of these subsystems in the elderly, compared to younger adults. The primary aim of the research is to discover whether certain subsystems are, relative to other subsystems, selectively more effective in senescence. The research aims to disprove the idea that cognitive aging can be understood solely in terms of "generalized slowing," showing that slowing with age differs for different subsystems. If so, then strategies that make use of relatively effective subsystems should be more useful for elderly people than strategies that rely on ineffective subsystems. The experiments designed here are a step toward using contemporary theory from cognitive neuroscience and techniques of task analysis from cognitive science to design new tests for cognitive efficiency in the senescence.